Hi. I'm new to this, so if you have time, could you talk me through your thought process while programming the sigil?

Absolutely!

The programming is actually very simple: there is a construct that is first programmed to be always around and draw energy on it's own, so there is no risk of it fading. Then, I programmed it to detect when a user begins focusing on the sigil, and when it does, it does two things: causes the user to become deeply focused (I specified deeply, psionically to emphasis what is needed), and gives the user energy it has collected.

As to how the programming is done, it's literally just specifying exactly what I said. You first get into a psionic focus, and have a deep expectation that what you are programming is true. I personally tend to recite the programming to myself over and over before becoming focused to get a clear feel about the programming, but it isn't needed. You just need a clear picture of what you want. It's really that easy: just expect that what you want is true.

(Also, fun fact, to enter the focus, I used the construct I was about to create before I actually created it. You can do fun stuff like that once you get the hang of it.)